1. Technical Field
The present invention relates to a dual fluid cartridge assembly and more particularly to a dual fluid cartridge assembly configured with an air vent for evacuating air during filling of the cartridge to eliminate trapped air pockets in the fluid to be dispensed.
2. Description of the Prior Art
Fluid cartridge assemblies are generally known in the art Both single and multiple fluid cartridge assemblies are known. An example of a single fluid cartridge assembly is disclosed in commonly owned international patent application No. PCT/US02/39041, filed on Dec. 6, 2002. Such a single fluid cartridge assembly is used to dispense a single fluid.
Dual fluid cartridge assemblies are also known. Examples of such dual fluid cartridge assemblies are disclosed in U.S. Pat. Nos. 4,220,261; 4,961,520; and 5,310,091. Such dual fluid cartridge assemblies are known to be used to dispense fluid materials, such as thermoset adhesives, which typically contain two components that need to remain separated and applied quickly after mixing. U.S. Pat. No. 5,310,091 discloses a dual fluid cartridge assembly configured with a front and rear chamber formed by an inner cartridge and an outer cartridge, respectively. Piston seals are used to separate the fluids within the cartridges. Movement of the inner cartridge, for example, under the influence of a plunger in a conventional caulking gun, causes the inner cartridge and upper piston to advance axially within the outer cartridge. The inner cartridge is in fluid communication with a hollow delivery tube which extends through a front chamber up to a cartridge outlet. Movement of the inner cartridge within the outer cartridge causes fluids in the inner cartridge and outer cartridge to be dispensed.
One problem associated with such dual fluid cartridge assemblies occurs during the fluid filling process. In particular, filling is initiated by forcing as much air as possible out of the inner and outer cartridge chambers prior to filling. The inner and outer cartridges are then back-filled with a fluid through the cartridge outlet Unfortunately, this method traps a quantity of air in both the inner and outer cartridge chambers. The trapped air forms air pockets in the fluid and causes many undesirable affects, such as non-uniform application of the fluids, as well as drooling after the fluid has been dispensed. In addition, trapped air bubbles in the final mixed product are known to provide unsatisfactory results of the dispensed fluids. Thus, there is a need for a dual fluid cartridge assembly which evacuates air during filling in order to prevent trapped air pockets within the fluid to be dispersed.